1. Field of the Invention
The present invention relates to a motor servo-system controller for driving a mechanical system, particularly to a controller having an auto-tuning function for automatically setting control gains.
2. Description of the Prior Art
FIG. 6 is a block diagram showing an example of the motor servo-system controller inserted in "From analog servo to digital servo" (Iwakane: Journal of Robotics Society of Japan, Vol. 7 No. 3, pp. 212-217, June 1989). In FIG. 6, numeral 1 is a motor, 2 is a mechanical system mounted on the motor 1. In this case, combination of the motor 1 and the mechanical system 2 is the control object. Numeral 3 is a position and speed detector for measuring the position and speed of the control objects 1 and 2, 4 is a current detector for measuring the current flowing through the motor 1, 5 is a current control section, 6 is a speed control section, 7 is a position control section, 11 is a position command value, 12 is a detected position value, 13 is a detected speed value, 14 is a detected current value, 15 is a position error, 16 is a speed command value, 17 is a speed error, 18 is a current command value, 19 is a current error, 20 is the current flowing through the motor 1, and 30d is a motor servo-system controller.
The following is the description of the operations. The motor servo-system controller 3d is used to control the trajectory of, for example, a machine tool or robot, in which the position command value 11 is generated from a desirable trajectory command value to operate the control objects 1 and 2 in accordance with the position command value 11. That is, the difference between the detected position value 12 detected by the detector 3 and the position command value 11 is calculated to obtain the position error 15 and a proper operation is executed in the position control section 7 to determine the speed command value 16.
Then, the difference between the detected speed value 13 obtained by the detector 3 and the speed command value 16 is calculated to obtain the speed error 17 and a proper operation is executed in the speed control section 6 to determine the current command value 18. Moreover, the difference between the detected current value 14 obtained by the current detector 4 and the current command value 18 is calculated to obtain the current error 19 and a proper operation is executed in the current control section 6 to determine the motor current 20.
For the above existing controller; P (proportional) operation and PI (proportional and integral) operation are executed in the position control section 7, speed control section 6, and current control section 5 respectively. Therefore, preferable trajectory control can be realized by constituting the motor servo-system controller 30d as the above mentioned and using proper gains corresponding to the control objects 1 and 2 for the operations by the control sections 5 through 7.